GB2180023A - A vehicle braking system - Google Patents

Abstract

A vehicle braking system comprises at each end of an axle, a first internal shoe drum brake (15, 23) in combination with a second internal shoe drum brake (3, 4) and/or a disc brake (36-40, Figure 2). The first drum brake is actuated via a linkage by a pneumatic cylinder (29) and the second drum brake or disc brake is actuated separately by hydraulic fluid pumped by an electric motor from a gearbox on the operation of an electric switch by the driver. The brake shoe support (4) of the second drum brake is removably mounted on the axle. <IMAGE>

Description

SPECIFICATION Vehicle braking system This invention relates to vehicle braking systems and is particularly applicable to the braking of heavy vehicles, including all types of trucks independent of the numberoftheirwheel axles.

Until the present time, by substantial contrastwith the present invention, electric neutralizers weighing 1.050 kg. and having a maximum braking torque of 250 kg. x m. are used together with auxiliary brakes and storage batteries as a brake energy source and have the typical problems of batteries during the winter. Also known is a multiple pinion multiplication device for the purpose of multiplying the revolutions of the wheel by five and transmitting itto magentic plates, which implies a highly troublesome complex mechanism and an energy consumption equivalent to 3.5% litres of gas-oil due to the charge loss in this multiplication.

Also known is an axle model with an hydraulic central brake with drums and brake shoes, the problem with which is the excess weight along its central cast iron frame, because the complete axle withouttyre rims weighs approximately 900 kg.

On the marketthere is also a disc axlewhich does not have a drum air brake and only brakes by use of a disc, reaching temperatures of up to 550 centrigrade; this does not therefore have a double safety factor like that of the brake of the present invention, which utilises a double drum, drum and disc.

The invention proposes to use the braking torque of an axle, which already has a traditional air braking system, consisting of brake shoes and a cam. Ac cording Iy, a second drum is mounted in abutment with the already existing drum so as to form first unit solidly connected therewith, there being in addition another unit consisting of brake shoes, an hydraulic cylinder and a fluted receiving support, which enters a fluted projecting support of an axle sleeve, the latter being fastened by a castellated nut.

The braking system of the invention may be emb odied by combining two drumsto be used on two- axle and double wheel chassis, or alternatively by combining a drum and a disc, to be used on three axle and single wheel chassis, increasing the braking effect by means of an hydraulic brake pad and a disc mounted on the outside rim ofthe air brake drum thus achieving a self-governing braking system inde pendent ofthe tyre, controlled from the vehicle cab by the driver by means of a switch. The control instructions are directed to an electro-distributor which applies the hydraulic pressure to the cylinders or pads which perform the braking function.

Both variations of the braking system work with a powertake-offfrom the vehicle gearbox with an electro-distributor pump tank controlled from the cab by low power electric instructions, so as efficiently to arrestthe motion of a high tonnagevehicle,without the need to use the conventional brakes or the braking effect of the motor.

The advantages ofthe invention with respect two hitherto known systems are noteworthy, the main one being the arrangement of the components, ac cording to which the truck, chassis or heavy vehicle may make use of the braking at several locations, to avoid dragging the wheels or skidding of the vehicle by wheel locking.At these locations it is possible to vary the hydraulic pressure transmitted to the brake shoe cylinders, proportional to the braking torque, which is done with a sensor located underneath the body of the vehicle which will automatically regulate the torque, when the driver causes the vehicle to brake, which also acts as a neutralizer upon being able to vary the working pressures. It weights app roximately 500 kgs. and has a braking torque of 1,100 kgs. x m. per axle, plus the air braketorque.

Independent of models which may be commerci ally made in the future, the braking unit is generally used on fouraxletrucks,two axle double wheel chassis, three axle single wheel chassis and heavy vehicles.

The braking system of the present invention by virtue of its simplicity and constructive logic, is trouble-free, and this is basically due to the fact that the gear operates at the revolution speeds deter mined by the movement of the vehicle, the friction braking being by operation of drums and disc, by means of brake shoes and brake linings and by brake pads in the disc version.

As a result of the above, additional advantages such as a reduction in the cost of wheels and a con siderable fuel saving, are obtained.

To enable the nature of the invention to be more clearly understood it is hereafter described with reference to the accompanying drawings which illustrate, by way of non-restrictive example two particularembodiments. In these drawings: Figure lisa longitudinal section of a braking axle which has been equipped with the double drum combination.

Figure2 is a longitudinal section of a braking axle which has been provided with the drum and disc combination.

Figure 3 shows a cross-sectional view ofthe braking system of the above figure.

Referring now to the drawings there can be seen an axle 2, which is essential to the system, having two plates 26 which are the seating for the laminated springs of the vehicle. Welded to the axle 2 is a brake shoe support 24, with its conventional pneumatic braking operating mechanisms, actuated from a pneumatic cylinder 29, that is to say brake shoe support pins 25, separators 35, a cam 27 which is moved by the pneumatic diaphragm through a control lever 28 and which movesthe brake shoes 15 with their corresponding brake linings into contact with the inside of the drum 23, the latter being connected to the wheel hub by the screws 22. The wheel hub 17 supports the wheels andtyre rims 21, and itturns on conical bearings 16 and 18 fastened by separators 20 and castellated nuts 12, with protective retainers 13 and 19.The sleeve 1 is the stationary bearing support which is force fitted in the axle 2 and may be integral therewith. Itcontainsthe bearings 16 and 18 and has screw threads 12, a fluted projecting part 9 and atthe end a male thread for the outside nut 9 which fastens the brake shoe support 4. At its outer end it also has a rapid socket 8 for receiving hydraulicfluid through a tube 30 which passes through the axle 2 and the sleeve 1, and which emerges through the hole 32to the T-piece 31, which the power take-off coming from the distributor reaches.

The external brake shoe support 4 is removable as it has a fluted receiving part 5 and is fastened by a castellated nut and washer. The brake shoes 14with their brake linings are supported by pins 7 and their separators, are energised from an hydraulic cylinder 6 fastened to the brake shoes by the bolts 34.

Recovery of the pneumatic as well as hydraulic brake shoes is accomplished by springs 41 and the fastening bolts 33.

A protection shield 10 which may also be provided with cooling holes is fastened to the brake shoes by means of screws 11. The drum 3 receives thefric- tional force from the brake linings of the outside brake shoe 4 and that is connected to the hub together with thetyre rim and inward drum 23.

In the disc-drum combination (Figure 3)the disc37 is screwed to the drum 23 by screws 38; the disc is braked from a brake pad 36 which has replaceable plates 39 and this unit is connected to the shaft 2 by means of a support40.

Likewise, the disc could be coupled to the double drum system.

Claims (5)

1. Avehicle braking system characterised buy a double braking drum at each end of an axle, one of them being conventional, while the other one is connected to the former, to the wheel hub and to thetyre rims set against each other, which may be housed in thetyre rims or may be independent, a pair of brake shoes with brake linings acting on each drum, the component parts ofthis second brake being anchored to the brake shoe support, which is fastened to a hollow cylindrical sleeve, which is a stationary bearing seating and is embedded in the axle, said connection being by means of a projecting fluted part and a receiving fluted part which have a hollow cylindrical body and a brake shoe support respectively and a nut which corresponds with a threaded section ofthe end of the hollow cylindrical body, hence remaining removable, the brake shoes with their linings being fastened to the said brake shoe supports by means of bolts and separators, and being movable by an hydraulic cylinder fastened to the brake shoes.

2. Avehicle braking system according to claim 1, characterised by races for conical bearings on the sleeve, the hub being the movable bearing part and supporting the wheels and the tyre rims turning on the above mentioned conical bearings.

3. Avehicle braking system according to claim 1, characterised by a hollow cylindrical body fastened to the axle having in the inside part of one end a rapid socket connected on the one hand to a brake shoe operating hydraulic cylinder and on the other hand to a powertake-off.

4. Avehicle braking system, according to claim 1 characterised by an inside brake drum able to be extended along its free surface to form an orthogonal tyre rim fastened thereto by means of screws, and a braking disc operated by a brake pad with brake plates and high pressure hydraulic control, said brake pad remaining fastened to the axle, in the event there is only one pair of wheels in the axle.

5. Avehicle braking system substantially as hereinbefore described with reference to and as shown in any of Figures 1 to 3 of the accompanying drawings.